In some engines, oil and combustion gases may flow past cylinder in the engine into an unsealed crankcase, thereby increasing vehicle emissions. Therefore, positive crankcase ventilation (PCV) systems have been developed to decrease vehicle emissions. The crankcase ventilation systems may include a sealed crankcase which vents crankcase gas into an intake conduit. At the same time, fresh air may be flowed into the sealed crankcase. In this way, air may be circulated through the crankcase and blow-by gases may be flowed to the intake system to reduce the amount of blow-by gasses emitted from the vehicle.
U.S. Pat. No. 8,347,865 discloses a PCV system including an oil separator in fluidic communication with an oil drain passage flowing oil separated from the blow-by gasses to an oil pan. However, the inventors have recognized several drawbacks with the PCV system disclosed in U.S. Pat. No. 8,347,865. The outlet of the oil drain passage may not be submerged in oil during some operating conditions. For instance, during cornering or other vehicle maneuvers the oil may be moved away from the outlet of the oil drain. Consequently, the oil drain passage may experience elevated pressures and oil may travel up the drain passage and past the oil separator into the intake system, increasing oil consumption in the engine and decreasing combustion efficiency.
The inventors herein have recognized the above issues and developed an engine system. The engine system includes an oil drain passage in fluidic communication with an oil separator. The engine system further includes a backflow valve positioned at an outlet of the oil drain line, the backflow valve having a first configuration where the valve provides a predetermined amount of oil backflow into the oil drain passage and a second configuration where the valve inhibits oil backflow into the oil drain passage.
In this way, a technical result of stopping or inhibiting oil backflow in the oil drain passage may accomplished during certain operating conditions and oil flow may be metered during other operating conditions. In one example, the first and second configurations may be implemented based on pressure in the sealed crankcase. An oil level stick may extend down the oil drain passage. In this way, the amount of oil may be ascertained by the vehicle operation when the backflow valve is in the first configuration. The first configuration may be initiated when a pressure in the crankcase is below a threshold value and the second configuration may be initiated when the pressure is above the threshold value. In this way, oil may flow into the oil drain passage during some conditions, enabling the oil level stick to be used as an oil level indicator and during other conditions oil backflow through the passage may be inhibited to reduce the likelihood of oil traveling through the drain passage into the intake system. As a result, combustion efficiency may be increased. The technical results achieved by the engine system include enabling an oil drain passage to be used for oil level indication as well as for a drain for separated oil and increasing the engine's combustion efficiency by reducing the likelihood of intake air contamination.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. Additionally, the above issues have been recognized by the inventors herein, and are not admitted to be known.